The Toronto Optimists was initially formed in 1952 as the 18th Scout Troop. This group became the 157th Scout Troop Trumpet Band and in 1956, with sponsorship from the Downtown Optimist Club, they became known as the Optimist Trumpet Band, nicknamed Opti.

With the 1956 Canadian Junior Novice competition, Opti began an unmatched string of championship victories. The corps leaped from being a class B standstill corps in 1957 to winning the Canadian National Junior Corps Championships in 1958, defeating Preston Scout House. Opti then went on to win ten more titles, through 1968. The Optimists’ unbroken streak of eleven consecutive championships is far longer than that of any other corps in drum corps history, American or Canadian.

The Optimists had the distinction of being the first Canadian corps to carry the newly-official maple leaf flag, on Feb. 27, 1965.

The uniform consisted of white bucks, black pants with a white stripe, a white sash and cumber bund, a green mother of pearl shako topped with a white plume and a green satin blouse with a white diagonal stripe bordered in black.

Also known as The Green Machine, the Optimists continued to compete into the 1970s, but De La Salle Oaklands had taken over their place as the power in Canadian drum corps by that time. Opti won one more Canadian Junior title, in 1972, but in the Spring of 1976 they merged with the Seneca Princemen to become the Seneca Optimists.